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Biomedical subjects

J S Yoon

Publications and source records attributed to J S Yoon.

At least 19 recordsLinked to original sources
PubMed2002

Association between CYP2D6 genotype and tardive dyskinesia in Korean schizophrenics.

The CYP2D6 gene codes for human cytochrome P450 2D6 enzyme, which is responsible for the metabolism of many psychiatric drugs. In schizophrenic patients treated with neuroleptics, decreased or loss of function CYP2D6 alleles may contribute to the development of tardive dyskinesia (TD), a movement disorder that frequently occurs with chronic neuroleptic treatment. The goal of this study was to determine whether the occurrence of TD is associated with CYP2D6 genotype in a cohort of Korean schizophrenics by employing a CYP450 GeneChip((R)) oligonucleotide microarray and PCR assays to screen for 19 CYP2D6 alleles. Our results revealed that males with at least one decreased or loss of function allele have a moderately greater chance of developing TD than males with only wild-type alleles. Female schizophrenics did not have a significantly greater chance of developing TD. Our results demonstrate the utility of CYP2D6 microarrays to assess genotype status in this Korean cohort.

Adolescent↗
PubMed2001

Predicting the emergence of antibiotic resistance by directed evolution and structural analysis.

Directed evolution can be a powerful tool to predict antibiotic resistance. Resistance involves the accumulation of mutations beneficial to the pathogen while maintaining residue interactions and core packing that are critical for preserving function. The constraint of maintaining stability, while increasing activity, drastically reduces the number of possible mutational combination pathways. To test this theory, TEM-1 beta-lactamase was evolved using a hypermutator E. coli-based directed evolution technique with cefotaxime selection. The selected mutants were compared to two previous directed evolution studies and a database of clinical isolates. In all cases, evolution resulted in the generation of the E104K/M182T/G238S combination of mutations ( approximately 500-fold increased resistance), which is equivalent to clinical isolate TEM-52. The structure of TEM-52 was determined to 2.4 A. G238S widens access to the active site by 2.8 A whereas E104K stabilizes the reorganized topology. The M182T mutation is located 17 A from the active site and appears to be a global suppressor mutation that acts to stabilize the new enzyme structure. Our results demonstrate that directed evolution coupled with structural analysis can be used to predict future mutations that lead to increased antibiotic resistance.

Amino Acid Sequence↗
PubMed2001

Toxicity and biodegradation of products from polyester hydrolysis.

Toxicity of products from polyester hydrolysis such as succinic acid (SA), adipic acid (AA), mandelic acid (MA), terephthalic acid (TA), 1,4-butanediol (1,4-B), ethylene glycol (EG), styrene glycol (SG) and 1,4-cyclohexane dimethanol (1,4-C) was evaluated by phytotoxicity test on germination of young radish seeds and by cytotoxicity test on HeLa cells. The phytotoxicity test revealed SG > MA > 1,4-C > AA approximately SA > TA approximately EG > 1,4-B in order of decreasing toxicity taking into consideration the growth behavior after germination as well as the percentage of germination. Toxicity on HeLa cells decreased in slightly different order compared to that on young radish seeds, i.e. SG > 1,4-C > MA > TA > SA > AA > EG > 1,4-B. Tests for the phytotoxicity and for cytotoxicity indicated that the aromatic compounds were more harmful than the aliphatic ones. Each group of 4 strains which grew most rapidly on each agar plate containing SA, AA, MA, TA, 1,4-B, EG, SG and 1,4-C respectively as a sole carbon source was identified by the fatty acid methyl esters analysis. The modified Sturm test was carried out using the single isolated strain, an activated sludge or a mixed soil to measure the rate of mineralization of the compounds into carbon dioxide. The aliphatic compounds were mineralized more easily than the aromatic compounds. 1,4-C showed the most exceptionally slow degradation. A scrutiny of residual 1,4-C after degradation is required before polyesters containing 1,4-C could be classified into compostable because 1,4-C has detrimental effects on young radish seeds and HeLa cells and has a tendency to accumulate in the environment due to its slow degradability.

Animals↗
PubMed2001

Vinorelbine-associated myelopathy in a patient who previously received paclitaxel: a case report.

Vinorelbine seems to cause less neurotoxicity than other vinca alkaloids because of its selective activity on mitotic cells over axonal microtubules. Clinical trials report very mild peripheral neurotoxicity with distal paresthesiae and there are no reports of myelopathy in these series of patients. The authors describe a patient who developed a rare event of myelopathy while on vinorelbine for non-small-cell lung cancer.

Antineoplastic Agents, Phytogenic↗
PubMed2000

Malignant hidroacanthoma simplex: a case report.

Hidroacanthoma simplex is a benign tumor of the skin originating from or showing differentiation to the sweat glands. It grossly resembles seborrheic keratosis of Bowen's disease and histologically shows intraepidermal focal growth of epithelial cells. Malignant transformation of this tumor is rare. We report a case of pigmented hidroacanthoma with malignant transformation in a 67-year-old woman. There was a 20-year history of a skin lesion on the right thigh, which first appeared as a small verrucous papule, progressed to a dark-brown colored patch, and then to a pigmented plaque. Histologically, the primary tumor was composed of small squamoid cells with marked cellular atypia. Most of the tumor cells were located in the epidermis. Immunohistochemically, the cytoplasm of some tumor cells showed a positive reaction for epithelial membrane antigen, but not for either carcino-embryonic antigen or the S-100 protein.

Acrospiroma↗
PubMed1999

Comparison of incidence of gastroesophageal reflux and regurgitation associated with timing of removal of the laryngeal mask airway: on appearance of signs of rejection versus after recovery of consciousness.

STUDY OBJECTIVES: To compare the incidence of gastroesophageal reflux and regurgitation associated with laryngeal mask airway (LMA) removal when signs of rejecting the LMA, such as swallowing, struggling, and restlessness, were observed and when the patient could open his or her mouth on command. DESIGN: Randomized clinical trial. SETTING: Operating room and recovery room of a tertiary care referral hospital. PATIENTS: 63 ASA physical status I and II adult patients scheduled for elective orthopedic surgery. INTERVENTIONS: Using a standardized general anesthetic technique, patients were allocated randomly to Group A (n = 34; LMA removed when signs of rejection, such as swallowing, struggling, and restlessness, were observed) or Group B (n = 29; LMA removed when the patient could open his or her mouth on command). MEASUREMENTS AND MAIN RESULTS: To detect gastroesophageal reflux throughout anesthesia, a pH monitoring probe was positioned in the lower esophagus on the day before surgery. To assess regurgitation during emergence, a gelatin capsule of methylene blue (50 mg) was swallowed prior to induction. At the end of anesthesia, episodes of reflux and regurgitation of gastric contents were analyzed/determined by pH below 4 and bluish staining of the pharynx and/or LMA, respectively. Physical events such as bucking, straining, and coughing during the arousal phase were recorded in both groups by an independent observer. The incidence of reflux (pH < 4) from the time of the appearance of rejection signs to LMA removal and the total incidence of reflux in Group B were significantly higher than in Group A (p < 0.05). Staining of the LMA and the pharynx by methylene blue was not observed in patients from either experimental group. The number of physical events in Group B during the arousal phase was significantly increased compared to Group A (p < 0.05). Considering all patients in Group A and Group B, physical events were associated with the occurrence of reflux (p < 0.05). Desaturation (SpO2 < 95%) and clinical evidence of aspiration of gastric contents did not occur in either group. CONCLUSION: Maintenance of the LMA until the patient can open his or her mouth on command increases the incidence of gastroesophageal reflux.

Adolescent↗
PubMed1999

Behcet's disease associated with myelodysplastic syndrome: a case report.

A rare case of Behcet's disease associated with myelodysplastic syndrome (MDS) is described. A 50-year-old Korean female suffering recurrent oral ulcer, genital ulcer, fatigue, arthralgia in both knees and fever was diagnosed as Behcet's disease. The findings of bone marrow aspirates were consistent with refractory anemia, a subtype of myelodysplastic syndrome. Chromosomal analysis of bone marrow cells revealed 46,XX,-8,-20,+der(8)t(8;20)(p23;p10),+der(8) t(8;20)(p23;q10)[30]. The chromosomal changes found in this patient were different from those of previous reports, which mostly revealed trisomy 8. If anemia, low reticulocyte count and dyspoietic cells are sustained in Behcet's disease, physicians should be alert to the possibility of MDS with aberration in chromosome 8 and perform a bone marrow study for the proper diagnosis and treatment of the disease. We presented a case of Behcet's disease associated with MDS, which is the first Korean case.

Anemia↗
PubMed1992

Riboflavin requirements and exercise adaptation in older women.

The effects of exercise training on riboflavin requirements and of riboflavin intake on endurance were examined in 14 women, 50-67 y of age, who participated in a 10-wk, two-period crossover exercise study at two riboflavin intakes, 0.15 micrograms/kJ (0.6 micrograms/kcal) and 0.22 micrograms/kJ (0.9 micrograms/kcal). Subjects exercised 20-25 min/d, 6 d/wk, for 4-wk periods on a cycle ergometer at 75-85% of their maximal heart rate. Riboflavin status was assessed by measuring the erythrocyte glutathione reductase activity coefficient (EGRAC) and urinary riboflavin excretion. Physical performance was evaluated by using a walking treadmill test to determine maximal oxygen capacity (VO2max) and anaerobic threshold by gas exchange (ATGE). Exercise significantly affected riboflavin status as EGRAC increased (P less than 0.001) and riboflavin excretion decreased (P less than 0.01) in both groups. VO2max increased significantly with exercise (P less than 0.01). However, changes in VO2max (L/min) and ATGE with exercise training were not different in the two groups. Riboflavin requirements of older women increased with exercise training, but increased riboflavin intake did not enhance improvements in endurance.

Aged↗
PubMed1985

Chemical mutagenesis testing in Drosophila. IV. Results of 45 coded compounds tested for the National Toxicology Program.

Results from Drosophila mutagenicity tests of 45 chemical compounds assayed for the National Toxicology Program are presented. Nine compounds were judged positive and four equivocal in the sex-linked recessive lethal test. The nine positive compounds were acetin, allyl glycidyl ether, cyclophosphamide, 1,2-dibromo-3-chloropropane, 2,3-dibromo-1-propanol, dimethylcarbamyl chloride, 1,2-epoxy-butane, lasiocarpine, and N-nitrosopiperidine. The results for chloral hydrate, maleic hydrazide, propantheline bromide, and trifluralin were equivocal. Of the nine compounds positive in recessive lethal induction, only two--allyl glycidyl ether and dimethylcarbamyl chloride--failed to induce translocations. The remaining 32 were judged to be nonmutagenic under the conditions used.

Animals↗
PubMed1983

IgG heavy-chain (Gm) allotypes and HLA-antigens in insulin-dependent diabetes mellitus in Korea.

Eighty-eight patients with insulin-dependent diabetes mellitus (IDDM) and seventy-two unrelated normal controls in Korea were studied for Gm allotypes and HLA-antigens. Ten Gm phenotypes were found among the Korean population. The phenotype frequencies of Gm axg (1,2,21), Gm ag (1,21), Gm agb0b3b5st (1,21, 11,13,10,15,16) and Gm agfb0b1b3b4b5 (1,21,3,11,5,13,14,10) were higher than the other Gm allotypes, but there was no significant difference between patients and controls. HLA-BW54 was found in 15% of patients who had any of those Gm allotypes (Gm axg, Gm agb0b3b5st, Gm ab0b3b5st). However there was no significant difference in frequency as compared with controls.

Diabetes Mellitus, Type 1↗
PubMed1976

Evolution of Hawaiian drosophilidae. II. Patterns and rates of chromosome evolution in an antopocerus phylogeny.

The phylogenetic relationships of seven species of the genus Antopocerus (Family Drosophilidae) have been determined by means of a study of the metaphase configurations and polytene chromosomes. Based on biogeographical, behavioral and cytogenetic information A. longiseta from Molokai is tentatively identified as the primitive species of the genus. The metaphase karyotypes of all Antopocerus species are either five pairs of rod chromosomes and a pair of dots (5R1D), or six rods (6R). Heterochromatin additions converted the dots to rods. Chromosome breakpoints for inversions also are clustered at heterochromatic loci. The chromosome segments between heterochromatic loci may represent sets of functionally related loci, evolving as a unit. The rate of chromosomal inversion substitution is estimated in the origin of the taxon (probably a subgenus of Drosophila rather than a separate genus). It averages no greater than one substitution per 1,000 years, or one per 5,000 generations. The average genetic death rate per generation of one individual per hundred is required to achieve this substitution rate. The rate of inversion substitution during radiation of this taxon may be only 4.4 X 10(-3) times as fast as that present in forming the taxon. Alternatively, radiation may have required only 250,000 years if rates of substitution are the same as in the origination of the taxon. Average rates of substitution reflect genetic accidents, selection pressures and rates of adaptation to new niches, as well as the rate of encountering new niches. Rate of adaptation probably is much greater in this instance than rate of encountering new niches. Rate of adaptation probably is much greater in this instance than rate of encountering new niches. Therefore, the average rate of evolution reflects more nearly biogeographic and ecological factors than genetic factors.

Animals↗